The present invention relates to systems and methods for sensing levels and electrical properties of liquids stored in fuel tanks and other containers. More particularly, this invention pertains to sensing liquid levels and properties by propagating electromagnetic waves into a liquid container.
Motor vehicle operators rely on fuel gauges to provide accurate information on the amount of fuel remaining in the fuel tank. The most common method of measuring the amount of fuel remaining in a motor vehicle fuel tank is to place a mechanical float and lever inside the tank. When the fuel level changes in the tank, the float causes the lever to pivot. When the lever pivots in response to changing fuel levels, an electrical signal is proportionately generated and/or varied. This variation in electrical signal is transmitted to a fuel gauge or vehicle data bus external to the tank. Such electromechanical fuel measurement systems are not particularly accurate and, of course, require installation of a mechanism inside the tank. Repair, replacement, or adjustment of an internal fuel level measurement mechanism is problematic.
Engine control systems in many motor vehicles, and particularly in flexible fuel vehicles, also have a need to know the type and/or composition of fuel that is inside the fuel tank. Conventional fuel composition sensors are complex, expensive, and are not capable of also measuring fuel levels.